There is a demand contract system as a contract system of an electricity rate which is made between an owner of a store or a facility and a power industry. According to the demand contract system, an integrating power consumption demand is calculated for every prescribed demand time period (ordinarily, 30 minutes), and the electricity rate is determined with a maximum integrating power consumption demand in the integrating power consumption demands of respective demand time periods in one year as a reference. Therefore, it is necessary to always restrain the integrating power consumption demand in one demand time period to be low.
Hence, Patent Literature 1 discloses a power monitoring device which performs control (demand control) of predicting an integrating power consumption demand from when a demand time period is started to when the demand time period is finished in the midst of the demand time period, and stopping operating a specific device in a case where a predicted value exceeds a prescribed contract power amount.
Also, Patent Literature 2 discloses a power monitoring device which configures energy conservation advice and gives the advice to a user in a case where a predicted value going to exceed to a prescribed contract power amount.
A power monitoring device which performs control of measuring power consumption or a power consumption amount and stopping operating a specific device in a case where the power consumption amount is going to exceed a contract ampere number is on sale also in a household.
These devices individually perform power monitoring, notification, and control in respective customers of respective stores or facilities, or respective households or the like, and are operated independently from a power utilization rate of a utility grid in which the power industry supplies power to respective customers.
On the other hand, Patent Literature 3 discloses a system for integrally controlling plural demand devices of plural customers communicating with a utility grid and leveling a power utilization rate of the power grid.